The present invention is directed to a device for measuring the thickness of a dry paint film applied to a plastic non-metallic substrate without destroying the paint film. In particular, the device may be used to measure the dry paint film thickness of a paint applied by conventional or electrostatic spraying to a plastic substrate primed with a conductive primer.
In the spray application of many paints particularly on plastic substrates, a relatively thin film is formed near the edge of the article being coated and is substantially thicker in the center of the article. This difference in thickness of the paint film results in appearance changes from the center to the edge of the article. This is a problem in the coating of articles, such as auto or truck body panels or facia, in which a uniform appearance is desired, and in particular is a problem for paint panels which are used as color standards in laboratories, paint manufacturing plants and automotive and truck assembly plants. In particular, rejects of paint panels to be used for color standards can be as high as 66% of the panels coated for such uses. Current methods for testing for film thickness destroy the film. There is no good and accurate non-destructive method or device for quickly and accurately measuring the paint film on a plastic substrate.
There is a need for a dry film thickness measuring device for plastic substrates which does not destroy the film and accurately measures the paint film thickness on plastic substrates.